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/* This file is completely threadsafe - keep it that way! */
#include "gmxpre.h"

#include "tgroup.h"

#include <cmath>

#include "gromacs/gmxlib/network.h"
#include "gromacs/math/vec.h"
#include "gromacs/mdlib/gmx_omp_nthreads.h"
#include "gromacs/mdlib/rbin.h"
#include "gromacs/mdlib/update.h"
#include "gromacs/mdtypes/group.h"
#include "gromacs/mdtypes/inputrec.h"
#include "gromacs/mdtypes/mdatom.h"
#include "gromacs/topology/mtop_util.h"
#include "gromacs/topology/topology.h"
#include "gromacs/utility/exceptions.h"
#include "gromacs/utility/fatalerror.h"
#include "gromacs/utility/futil.h"
#include "gromacs/utility/smalloc.h"

static void init_grpstat(const gmx_mtop_t* mtop, int ngacc, t_grp_acc gstat[])
{
    if (ngacc > 0)
    {
        const SimulationGroups& groups = mtop->groups;
        for (const AtomProxy atomP : AtomRange(*mtop))
        {
            const t_atom& local = atomP.atom();
            int           i     = atomP.globalAtomNumber();
            int           grp   = getGroupType(groups, SimulationAtomGroupType::Acceleration, i);
            if ((grp < 0) && (grp >= ngacc))
            {
                gmx_incons("Input for acceleration groups wrong");
            }
            gstat[grp].nat++;
            /* This will not work for integrator BD */
            gstat[grp].mA += local.m;
            gstat[grp].mB += local.mB;
        }
    }
}

void init_ekindata(FILE gmx_unused*  log,
                   const gmx_mtop_t* mtop,
                   const t_grpopts*  opts,
                   gmx_ekindata_t*   ekind,
                   real              cos_accel)
{
    int i;

    /* bNEMD tells if we should remove remove the COM velocity
     * from the velocities during velocity scaling in T-coupling.
     * Turn this on when we have multiple acceleration groups
     * or one accelerated group.
     */
    ekind->bNEMD = (opts->ngacc > 1 || norm2(opts->acc[0]) > 0);

    ekind->ngtc = opts->ngtc;
    ekind->tcstat.resize(opts->ngtc);
    /* Set Berendsen tcoupl lambda's to 1,
     * so runs without Berendsen coupling are not affected.
     */
    for (i = 0; i < opts->ngtc; i++)
    {
        ekind->tcstat[i].lambda         = 1.0;
        ekind->tcstat[i].vscale_nhc     = 1.0;
        ekind->tcstat[i].ekinscaleh_nhc = 1.0;
        ekind->tcstat[i].ekinscalef_nhc = 1.0;
    }

    int nthread     = gmx_omp_nthreads_get(emntUpdate);
    ekind->nthreads = nthread;
    snew(ekind->ekin_work_alloc, nthread);
    snew(ekind->ekin_work, nthread);
    snew(ekind->dekindl_work, nthread);
#pragma omp parallel for num_threads(nthread) schedule(static)
    for (int thread = 0; thread < nthread; thread++)
    {
        try
        {
#define EKIN_WORK_BUFFER_SIZE 2
            /* Allocate 2 extra elements on both sides, so in single
             * precision we have
             * EKIN_WORK_BUFFER_SIZE*DIM*DIM*sizeof(real) = 72/144 bytes
             * buffer on both sides to avoid cache pollution.
             */
            snew(ekind->ekin_work_alloc[thread], ekind->ngtc + 2 * EKIN_WORK_BUFFER_SIZE);
            ekind->ekin_work[thread] = ekind->ekin_work_alloc[thread] + EKIN_WORK_BUFFER_SIZE;
            /* Nasty hack so we can have the per-thread accumulation
             * variable for dekindl in the same thread-local cache lines
             * as the per-thread accumulation tensors for ekin[fh],
             * because they are accumulated in the same loop. */
            ekind->dekindl_work[thread] = &(ekind->ekin_work[thread][ekind->ngtc][0][0]);
#undef EKIN_WORK_BUFFER_SIZE
        }
        GMX_CATCH_ALL_AND_EXIT_WITH_FATAL_ERROR
    }

    ekind->ngacc = opts->ngacc;
    ekind->grpstat.resize(opts->ngacc);
    init_grpstat(mtop, opts->ngacc, ekind->grpstat.data());

    ekind->cosacc.cos_accel = cos_accel;
}

void accumulate_u(const t_commrec* cr, const t_grpopts* opts, gmx_ekindata_t* ekind)
{
    /* This routine will only be called when it's necessary */
    t_bin* rb;
    int    g;

    rb = mk_bin();

    for (g = 0; (g < opts->ngacc); g++)
    {
        add_binr(rb, DIM, ekind->grpstat[g].u);
    }
    sum_bin(rb, cr);

    for (g = 0; (g < opts->ngacc); g++)
    {
        extract_binr(rb, DIM * g, DIM, ekind->grpstat[g].u);
    }
    destroy_bin(rb);
}

void update_ekindata(int              start,
                     int              homenr,
                     gmx_ekindata_t*  ekind,
                     const t_grpopts* opts,
                     const rvec       v[],
                     const t_mdatoms* md,
                     real             lambda)
{
    int  d, g, n;
    real mv;

    /* calculate mean velocities at whole timestep */
    for (g = 0; (g < opts->ngtc); g++)
    {
        ekind->tcstat[g].T = 0;
    }

    if (ekind->bNEMD)
    {
        for (g = 0; (g < opts->ngacc); g++)
        {
            clear_rvec(ekind->grpstat[g].u);
        }

        g = 0;
        for (n = start; (n < start + homenr); n++)
        {
            if (md->cACC)
            {
                g = md->cACC[n];
            }
            for (d = 0; (d < DIM); d++)
            {
                mv = md->massT[n] * v[n][d];
                ekind->grpstat[g].u[d] += mv;
            }
        }

        for (g = 0; (g < opts->ngacc); g++)
        {
            for (d = 0; (d < DIM); d++)
            {
                ekind->grpstat[g].u[d] /=
                        (1 - lambda) * ekind->grpstat[g].mA + lambda * ekind->grpstat[g].mB;
            }
        }
    }
}

real sum_ekin(const t_grpopts* opts, gmx_ekindata_t* ekind, real* dekindlambda, gmx_bool bEkinAveVel, gmx_bool bScaleEkin)
{
    int           i, j, m, ngtc;
    real          T;
    t_grp_tcstat* tcstat;
    real          nrdf, nd, *ndf;

    ngtc = opts->ngtc;
    ndf  = opts->nrdf;

    T    = 0;
    nrdf = 0;

    clear_mat(ekind->ekin);

    for (i = 0; (i < ngtc); i++)
    {

        nd     = ndf[i];
        tcstat = &ekind->tcstat[i];
        /* Sometimes a group does not have degrees of freedom, e.g.
         * when it consists of shells and virtual sites, then we just
         * set the temperatue to 0 and also neglect the kinetic
         * energy, which should be  zero anyway.
         */

        if (nd > 0)
        {
            if (bEkinAveVel)
            {
                if (!bScaleEkin)
                {
                    /* in this case, kinetic energy is from the current velocities already */
                    msmul(tcstat->ekinf, tcstat->ekinscalef_nhc, tcstat->ekinf);
                }
            }
            else
            {
                /* Calculate the full step Ekin as the average of the half steps */
                for (j = 0; (j < DIM); j++)
                {
                    for (m = 0; (m < DIM); m++)
                    {
                        tcstat->ekinf[j][m] = 0.5
                                              * (tcstat->ekinh[j][m] * tcstat->ekinscaleh_nhc
                                                 + tcstat->ekinh_old[j][m]);
                    }
                }
            }
            m_add(tcstat->ekinf, ekind->ekin, ekind->ekin);

            tcstat->Th = calc_temp(trace(tcstat->ekinh), nd);
            tcstat->T  = calc_temp(trace(tcstat->ekinf), nd);

            /* after the scaling factors have been multiplied in, we can remove them */
            if (bEkinAveVel)
            {
                tcstat->ekinscalef_nhc = 1.0;
            }
            else
            {
                tcstat->ekinscaleh_nhc = 1.0;
            }
        }
        else
        {
            tcstat->T  = 0;
            tcstat->Th = 0;
        }
        T += nd * tcstat->T;
        nrdf += nd;
    }
    if (nrdf > 0)
    {
        T /= nrdf;
    }
    if (dekindlambda)
    {
        if (bEkinAveVel)
        {
            *dekindlambda = ekind->dekindl;
        }
        else
        {
            *dekindlambda = 0.5 * (ekind->dekindl + ekind->dekindl_old);
        }
    }
    return T;
}
